agent: builder model: opus max_turns: 70 budget_usd: 15 —
fn parameter is lent with & (blocks K3a part 2)Score: bug before move; the last of #1023’s three defects, it blocks the self-hosting row K3a (k3a2’s precondition). Steps 1 and 3 of #1023 are on develop (3b6bf8c7, 90d7e2ad); b1023 stopped on this one because its cause is in the checker, outside its file list. This brief allows the checker files.
&_, found closure”; must print 2)fn alt(name: String) -> i64? sync { return name.len() }
fn use_it(known: fn(ref String) -> i64? sync) -> i64 sync { return known("ab") ?? 0 }
fn outer(known: fn(ref String) -> i64? sync) -> i64 sync {
let known = fn(name) { known(name) ?? alt(name) }
return use_it(known)
}
fn main() { println(f"{outer(fn(name) { null })}") }Without the shadowing (let more = ...; use_it(more)) it writes &more.
CheckState::a_lent_parameter (crates/nikaia-std/src/tools/check_fields.nika:213) matches a Variable to the walked function’s signature parameters by name only. The local known that shadows the parameter known reads as the lent parameter, so the_compiler_writes_the_reference (check_references.nika:295, Nor does a function this function was lent) writes no &. state.run_code already follows shadowing (check_core_stmt.nika:500-502); a_lent_parameter does not.
A name is the parameter only while its innermost binding is the parameter’s own: a_lent_parameter answers false when the innermost binding of the name lies in a frame deeper than the function’s parameter frame (the frame check_function.nika:733 pushes; a lambda’s own frames lie deeper, but a capture of the parameter inside a lambda still finds the binding in the parameter frame, so it stays the parameter). Fix it in a_lent_parameter itself, so its other callers (check_arm_leaves.nika:622, :629) get the same answer. If the frame index is not known at that point, add one field to CheckState (check_state.nika) set where the frame is pushed and restored after, like run_code.
lower-std (fixpoint clean), cargo check --profile fast -p nikaia-std --features compiler clean. Test tests/compiler/tests/a_shadowing_lambda_is_lent.nika (the probe, .stdout 2). Still pass: a_lambda_handed_round_a_cycle_runs, a_recursive_function_hands_a_new_lambda_to_itself, a_trait_method_*, a_method_hands_its_callback_to_a_function, and the guard set of .claude/agents/builder.md. Commit checker: a let that shadows a fn parameter is not the lent parameter (Fixes #1023).The test passes through nikaia test, the tests named above pass, gate green, pushed. Changelog: one line (a let lambda that shadows a fn parameter is lent with &).
An edit outside crates/nikaia-std/src/tools/check_fields.nika, check_state.nika, check_function.nika, check_references.nika and their lowering (lowered/*.rs, lowered.rs), and the new test; the probe still fails after the fix with a cause in the emitter (report it under Found: with the lowered line); an error in another agent’s file.
Not yours, never stage: every file git status shows modified or untracked at your start (among them crates/rs2nika/convert/nikaia.*, docs/selfhosting-plan.md), and every docs/briefs/* file except your report. If lowered.rs shows another hunk, stage only yours.
docs/builder-facts.md first. develop in the main checkout; git status at start: other agents’ uncommitted files are not yours, never touch or stage them.git add <files> only; commit after each step; git push origin develop fast-forward, no rebase (rejected: report Pushed: rejected, go on committing).cargo fmt, cargo clippy --all-targets -- -D warnings, scripts/pre-push-check.sh, and the gate of .claude/agents/builder.md (#852).CHANGELOG.md, badges; no new NK code. New tests in Nikaia only; never the full suite. No foreground sleep, no polling; scripts in files.std or the toolchain lacks stops the work: no code around it unless an ADR or Part I-III refuses it (name it). Else Result: blocked, Found: gap + probe, Needs: owner decision (CLAUDE.md, A missing form stops the work).NIKAIA_CACHE_LIMIT=2G; at most two clones with target/ in the machine; delete your own clone’s target/ and target/release/nikaia-scratch at the end; report GB freed.Pushed: line names the pushed sha. A report without a Pushed: line, or with a placeholder left in (TC, DISK), is not done and cuts the batch (k3a1 2026-10-29: Result: done, nothing committed)./home/user/Nikaia/docs/briefs/b1023b-shadowing-lambda-lent.md.report.md)Fields of docs/architect.md, Briefs and reports: Result: done|noop|partial|blocked (the bare word alone on that line: Result: done, never a summary after it, which cuts the batch, b869a 2026-10-27; Owner: is a question for the owner or none, never a role), Files, Commit, Body (optional, one paragraph for the commit message), Fixes, Pushed, Tests, Gate (green|red), Deviation, Found, Needs, Changelog, Owner, Disk freed, and for a move Rs2nika: (the kept N of M lines of rs2nika --score, then the three costliest hand edits; none for a task that moves no Rust, none (redesign) for a brief with Shape: redesign and no Convert: line). none where nothing, and then the bare word: Deviation: none (a note) cuts the batch (batch.nika compares exactly); a note goes into the commit message. Found: is only for a defect outside your change (it cuts the batch); a process event such as another session resetting or rewriting your files is no Found:, it goes under Needs: (m3a 2026-10-28); a converter draft that came out wrong is no Found:, it is one of the costliest edits under Rs2nika:, which the converter lane reads (e12-4b 2026-10-27); how you solved your own step goes into the commit message. Deviation: is only a step of the brief built otherwise than written or not built (a choice the brief left to you, such as keep what X needs and say so, is no deviation: it goes into the commit message; nor is building two steps in one commit when every step is built, e12-3a 2026-10-27, nor a step another commit on develop already built, shown by your test failing with that commit’s change reverted, b889 2026-10-27: name the commit in Body:, nor a test’s expected .stdout/.stderr taken from what the program really prints where the brief’s sketch of it was short or wrong, b934 2026-10-29: say so in Body:, nor a lowering that follows the ADR governing it where the brief’s expected lowering contradicts that ADR, b933 2026-10-29: name the ADR in Body:, nor re-keying an allow-list entry (KNOWN) whose hash changed for the same program and the same reason, b-fixforward-sweep2 2026-10-28: say so in Body:); how you verified (e.g. a test not run against the unfixed compiler) goes under Tests:. A noop says why under Tests: (what was probed), not under Deviation:. Final answer, one line: done <sha>, report <path> (or BLOCKED: ... / PUSH REJECTED ...).
Attribution: Co-Authored-By: Claude Opus 5.5 noreply@anthropic.com Claude-Session: https://claude.ai/code/session_01GFeMqxRbtUMiGVyDMxsvEq